The present invention relates to the feeding of filamentary material and, in particular, to methods and apparatus for preventing lapping of filamentary material around a front roll cot during a ring spinning operation.
A typical position in a ring spinning system comprises a roving bobbin that supplies a roving or filament bundle to a drafting apparatus which advances the apparatus to a spinning bobbin. The drafting apparatus commonly includes a pair of rotatably driven back drafting rolls which grip and pull the bundle from the roving bobbin. The bundle then passes between a pair of aprons and then through the nip of a pair of upper and lower front drafting rolls which include rubber sheaths or cots on their outer surfaces.
Occasionally, one of the filament bundles being drafted may break, the break usually occurring downstream of the front drafting rolls. The filament bundle continues to be supplied from the roving bobbin and is conducted to waste by a pneumatic aspirator or pneumafil located immediately downstream of the lower front drafting roll. It may occur, however, that a filament may adhere to one of the front drafting rolls, usually the top front drafting roll, and rotate therewith. That filament may pull other filaments from the bundle which then lap around the cot of the top front drafting roll. Such roll lapping will continue until the operator has an opportunity to cut and discard the lapped filaments and re-string the bundle. As a result of the time wasted in cutting the lapped filaments, production time is lost. Also, the rubber cot may be damaged when the operator is cutting loose the lapped filaments.
In an effort to resist the occurrence of roll lapping, anti-lapping procedures have been heretofore proposed in the art and are exemplified in U.S. Pat. Nos. 2,858,576; 3,757,381; 3,771,198; 3,772,738; 3,924,297; and 4,176,514. Such proposals include the positioning of a scraper or a rotary wheel such that an edge of the scraper or a plurality of flexible ribs on the wheel contact the outer periphery of the drafting roll to dislodge filaments therefrom. However, such devices add to the overall expense and mechanical complexity of the system and may produce premature wearing of the cot.